Method and apparatus for random access in NTN

Abstract

Methods and apparatuses of UE for performing random access procedures in NTN. A method of a UE comprises: identifying configuration information including a first and second set of resources for a RACH operation; determining whether current location information of the UE is valid for the RACH operation; selecting the first set of resources based on a determination that the current location information of the UE is valid; selecting the second set of resources based on a determination that the current location information of the UE is invalid; transmitting a RACH preamble on the selected first or second set of resources; and receiving, in response to transmitting the RACH preamble, a RAR MAC PDU. The RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources.

What is claimed is: 
     
       1. A user equipment (UE) in a wireless communication system, the UE comprising:
 a processor configured to:
 identify configuration information including a first set of resources and a second set of resources for a random access channel (RACH) operation, 
 determine whether current location information of the UE is valid for the RACH operation, 
 select the first set of resources based on a determination that the current location information of the UE is valid, and 
 select the second set of resources based on a determination that the current location information of the UE is invalid; and 
 
 a transceiver operably coupled to the processor, the transceiver configured to:
 transmit a RACH preamble on the selected first or second set of resources, and 
 receive, in response to transmission of the RACH preamble, a random access response (RAR) medium access control protocol data unit (MAC PDU) (RAR MAC PDU), 
 
 wherein the RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources. 
 
     
     
       2. The UE of  claim 1 , wherein the processor is further configured to:
 select the RACH preamble from a first set of RACH preambles configured for the first set of resources; or 
 select the RACH preamble from a second set of RACH preambles configured for the second set of resources. 
 
     
     
       3. The UE of  claim 1 , wherein the processor is further configured to:
 select a RACH frequency from a first set of RACH frequencies configured for the first set of resources; or 
 select the RACH frequency from a second set of RACH frequencies configured for the second set of resources. 
 
     
     
       4. The UE of  claim 1 , wherein the processor is further configured to:
 select a RACH time instance from a first set of RACH time instances configured for the first set of resources; or 
 select the RACH time instance from a second set of RACH time instances configured for the second set of resources. 
 
     
     
       5. The UE of  claim 1 , wherein the processor is further configured to:
 determine whether a value of a RAPID field included in the MAC subPDU indicates the first set of resources or the second set of resources; 
 decode the first format of the MAC subPDU based on a determination that the value of the RAPID field included in the MAC subPDU indicates the first set of resources; and 
 decode the second format of the MAC subPDU based on a determination that the value of the RAPID field included in the MAC subPDU indicates the second set of resources. 
 
     
     
       6. The UE of  claim 1 , wherein the processor is further configured to:
 determine whether a value of a reserved (R) field included in the MAC subPDU indicates the first set of resources or the second set of resources; 
 decode the first format of the MAC subPDU based on a determination that the value of the R field included in the MAC subPDU indicates the first set of resources; and 
 decode the second format of the MAC subPDU based on a determination that the value of the R field included in the MAC subPDU indicates the second set of resources. 
 
     
     
       7. The UE of  claim 1 , wherein:
 the transceiver is further configured to receive a physical downlink control channel (PDCCH) including a random access-radio network temporary identification (RA-RNTI) that is used to schedule a reception of the RAR MAC PDU; and 
 the processor is further configured to:
 determine whether the RA-RNTI included in the PDCCH indicates the first set of resources or the second set of resources, 
 decode the first format of the MAC subPDU based on a determination that the RA-RNTI indicates the first set of resources, and 
 decode the second format of the MAC subPDU based on a determination that the RA-RNTI indicates the second set of resources. 
 
 
     
     
       8. The UE of  claim 1 , wherein:
 the first format of the MAC subPDU includes a first length of a timing advance (TA) command field and the second format of the MAC subPDU includes a second length of a TA command field; and 
 the second length of the TA command field is longer than the first length of the TA command field. 
 
     
     
       9. The UE of  claim 1 , wherein:
 a value of a timing advance (TA) command field in the first format of the MAC subPDU is identified using a first granularity, and 
 the value of the TA command field in the second format of the MAC subPDU is identified using a second granularity. 
 
     
     
       10. A method of operating a user equipment (UE), the method comprising:
 identifying configuration information including a first set of resources and a second set of resources for a random access channel (RACH) operation; 
 determining whether current location information of the UE is valid for the RACH operation; 
 selecting the first set of resources based on a determination that the current location information of the UE is valid; 
 selecting the second set of resources based on a determination that the current location information of the UE is invalid; 
 transmitting a RACH preamble on the selected first or second set of resources; and 
 receiving, in response to transmitting the RACH preamble, a random access response (RAR) medium access control protocol data unit (MAC PDU) (RAR MAC PDU), 
 wherein the RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources. 
 
     
     
       11. The method of  claim 10 , further comprising:
 selecting the RACH preamble from a first set of RACH preambles configured for the first set of resources or the RACH preamble from a second set of RACH preambles configured for the second set of resources; 
 selecting a RACH frequency from a first set of RACH frequencies configured for the first set of resources or the RACH frequency from a second set of RACH frequencies configured for the second set of resources; and 
 selecting a RACH time instance from a first set of RACH time instances configured for the first set of resources or the RACH time instance from a second set of RACH time instances configured for the second set of resources. 
 
     
     
       12. A base station (BS) in a wireless communication system, the BS comprising:
 a processor configured to generate configuration information including a first set of resources and a second set of resources for a random access channel (RACH) operation; and 
 a transceiver configured to:
 transmit the configuration information including the first set of resources and the second set of resources for the RACH operation, 
 receive a RACH preamble on the first or second set of resources; and 
 transmit, in response to receiving the RACH preamble, a random access response (RAR) medium access control protocol data unit (MAC PDU) (RAR MAC PDU), 
 
 wherein the RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources, and 
 wherein the first set of resources is for when current location information of a user equipment (UE) is valid and the second set of resources is for when the current location information of the UE is invalid. 
 
     
     
       13. The BS of  claim 12 , wherein:
 the RACH preamble is from a first set of RACH preambles configured for the first set of resources; or 
 the RACH preamble is from a second set of RACH preambles configured for the second set of resources. 
 
     
     
       14. The BS of  claim 12 , wherein:
 a RACH frequency is from a first set of RACH frequencies configured for the first set of resources; or 
 the RACH frequency is from a second set of RACH frequencies configured for the second set of resources. 
 
     
     
       15. The BS of  claim 12 , wherein:
 a RACH time instance is from a first set of RACH time instances configured for the first set of resources; or 
 the RACH time instance is from a second set of RACH time instances configured for the second set of resources. 
 
     
     
       16. The BS of  claim 12 , wherein:
 the processor is further configured to generate the MAC subPDU including a value of a RAPID field, the value of the RAPID field included in the MAC subPDU indicating the first set of resources or the second set of resources; 
 the first format of the MAC subPDU is decoded based on that the value of the RAPID field included in the MAC subPDU indicates the first set of resources; and 
 the second format of the MAC subPDU is decoded based on that the value of the RAPID field included in the MAC subPDU indicates the second set of resources. 
 
     
     
       17. The BS of  claim 12 , wherein:
 the processor is further configured to generate the MAC subPDU including a value of a reserved (R) field, the value of the R field included in the MAC subPDU indicates the first set of resources or the second set of resources; 
 the first format of the MAC subPDU is decoded based on that the value of the R field included in the MAC subPDU indicates the first set of resources; and 
 the second format of the MAC subPDU is decoded based on that the value of the R field included in the MAC subPDU indicates the second set of resources. 
 
     
     
       18. The BS of  claim 12 , wherein:
 the transceiver is further configured to transmit a physical downlink control channel (PDCCH) including a random access-radio network temporary identification (RA-RNTI) that is used to schedule a reception of the RAR MAC PDU, the RA-RNTI included in the PDCCH indicating the first set of resources or the second set of resources; 
 the first format of the MAC subPDU is decoded based on that the RA-RNTI indicates the first set of resources; and 
 the second format of the MAC subPDU is decoded based on that the RA-RNTI indicates the second set of resources. 
 
     
     
       19. The BS of  claim 12 , wherein the processor is further configured to generate the first format of the MAC subPDU including a first length of a timing advance (TA) command field and the second format of the MAC subPDU including a second length of a TA command field, the second length of the TA command field being longer than the first length of the TA command field. 
     
     
       20. The BS of  claim 19 , wherein:
 a value of a timing advance (TA) command field in the first format of the MAC subPDU is identified using a first granularity, and 
 the value of the TA command field in the second format of the MAC subPDU is identified using a second granularity.